Study on analysis of crystal structure in CeO2 doped with Er2O3 or Gd2O3

To simulate the effects of burnable poison doping in nuclear fuel UO2, Er2O3 (or Gd2O3)-doped CeO2 pellets were prepared. Changes in lattice constant and atomic disordering for CeO2 due to the Er2O3 and Gd2O3 doping were measured by means of XRD and XAFS. By the Er2O3 doping, the lattice constant decreased, and a disordering of lattice structure was induced in the samples. The doping with Er2O3 also induced the disordering of atomic arrangement around Er atoms, which was observed through the change in XAFS spectra. In contrast, the effect of Gd2O3 doping was smaller than that of Er2O3 doping. The result was discussed in terms of ionic size of dopants in CeO2 crystal.